The present invention is directed to detecting radioactive materials that may be inside containers or otherwise shielded.
Efforts are underway to develop technologies capable of detecting the presence of materials that may be placed inside a container for purposes of transporting the material to a destination. Examples of harmful materials that may be most important to identify are radioactive, explosive, biological, and/or chemical agents.
Current radioisotopic identification is based upon peak-finding and pattern-matching algorithms. These techniques may be sufficient in the laboratory and in some industrial applications (e.g., in commercial nuclear power reactors), but they fall short in attempts to detect shielded radioisotopes in transit, largely because current algorithms do not sufficiently account for the interaction between the emitted radiation and the surrounding matter. The principal difficulties in developing isotopic identification software are twofold.
First, generally speaking, the detected spectra of shielded radioisotopes are weak and potentially buried in noise from, for example, natural background radiation and radiation emanating from nearby naturally radioactive legal sources (e.g., bananas, cat litter, medical isotopes). These weak spectra are difficult to analyze, since one of the main restrictive conditions of research in this area is that the flow of commerce not be unduly delayed by the detection process. Therefore, the longer detector integration times that would be used to obtain stronger signals are not practical in real-world applications. However, even with stronger signals, it is not clear that shielded radioisotopes, including some considered to be dangerous, can be located.
Second, the detection and identification of particular radioisotopes depends upon the interaction of the radiation with its surroundings. This environmental interaction is generally unknown and consequently is one of the most difficult aspects of the radioisotope detection and identification scenario. Analysis techniques that are currently used ignore the impact of surrounding materials in attempting to detect and identify threat radioisotope materials in a container or an otherwise shielded environment.
What is needed is a technique to analyze the radiation signature data (in the form of a spectrum) from any available detector device in order to rapidly and accurately determine the presence of a threat material in a space.